CHEMISTRY SECTION K

1. Which one of the following is not a chemical change?

(a)    Burning of coal in air

(b)   Fermentation of sugar cane Juice

(c)    Crystallization of table salt from sea water

(d)   Cracking of petroleum

              2. Metal used to make wires for safety fuses must hav

(a)      Very low resistivity and high melting point

(b)   High resistivity and low melting point

(c)    Low resistivity and low melting point

(d)   High resistivity and high melting point

              3. Mixture of which one of the following pairs of gases is the cause of occurrence of most of the explosions in mines?

(a)    Hydrogen and oxygen

(b)   Oxygen and acetylene

(c)    Methane and air

(d)   Carbon dioxide and methane

            4. Which one of the following pairs of metals constitutes the lightest metal and the heaviest metal, respectively?

(a)    Lithium and mercury

(b)   Lithium and osmium

(c)    Aluminum and osmium

(d)   Aluminum and mercury

            5. Consider the following statements about diamond

1.       It is used as a gem in jewellery because of its ability to reflect light.

2.       It is good conductor of electricity.

3.       It is used for cutting glass, marble stones and other hard materials.

4.       It is used for drilling of rocks.

Which of the statements given above is / are correct?

                             (a)    1,  3 and 4

                             (b)   2,  3 and 4

                             (c)    1,  2 and 3

                             (d)   2 and 4

Directions: (Q.Nos. 6-9) in the questions given below are two statement labeled as Assertion (A) and Reason which one of the following is correct?

Codes

(a)    Both A and R are true and R is  the correct explanation of A

(b)   Both A and R are true, but R is not the correct explanation of A

(c)    A is true , but R is false

(d)   A is false, but R is true

         6. Assertion (A) Soaps do not form lather with water containing salts of calcium and magnesium.

Reason (R) Calcium and magnesium salts of long chain fatty acids are insoluble in water.

         7. Assertion (A) Diamond is a good conductor of electricity.

Reason (R) Diamond and graphite are two allotropes of carbon and graphite is a good conductor of electricity.

          8. Assertion (A) the main constituent of the liquefied petroleum gas is methane.

Reason (R) Methane can be used directly for burning in homes and factories where it can be supplied thorough pipelines.

          9. Assertion (A) carbon Dioxide is a compound.

Reason (R) carbon and oxygen combine together in the ratio 3:8 by mass.

          10. To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium?

1.       Thorium is far more abundant in nature than uranium

2.       On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium.

3.       Thorium produces less harmful water compared to uranium.

Which of the statement (s) given above is / are correct?

(a)    Only 1

(b)   2 and 3

(c)    1 and 3

(d)   All of these

                      Answer:

1.       C

2.       C

3.       C

4.       B

5.       A

6.       A

7.       D

8.       D

9.       A

10.   D